The invention relates to a device for detecting radiation comprising a semiconductor device having a semiconductor body with at least one radiation-sensitive element at its surface which can be exposed to radiation to be detected, said radiation-sensitive element comprising sub-elements for converting radiation to be detected into generated charge.
Such a device is described in non-prepublished Netherlands Patent Application No. 8003906. In this connection, radiation may be considered to be light, ultraviolet radiation or infrared radiation and, for example, X-ray radiation or electron radiation.
A device of the kind mentioned above may be used for controlling the diameter of the radiation energy of a radiation beam, or for focusing such a beam.
In this case the beam to be adjusted may originate from a scene to be displayed, for example, in a camera; the adjusting plane in this case usually is a plane in the camera where a photosensitive plate may be present. The beam may also be a reading beam or a writing beam for use in display apparatus and pick-up apparatus, respectively, of video disks, audio disks or disks in behalf of information storage (VLP, compact disk and DOR, respectively), in which the adjusting plane is formed by a plane at the area of the video or audio disk and the information carrier respectively.
The invention also relates to a semiconductor device suitable for use in a device as mentioned above.
The above-mentioned Netherlands Patent Application shows inter alia a radiation-sensitive semiconductor device for spectroscopic applications having a number of juxtaposed sub-elements each connected to an external voltage source via an individual resistor. When as a result of incident radiation a photoelectric current is generated in one of the sub-elements, the voltage drop as a result of said currents causes a signal across the associated resistor. The place of the incident radiation can be determined by means of this signal. The value of the output signal is a measure of the quantity of charge generated in the associated sub-element and hence of the energy of the radiation incident on said sub-element. The device shown is directed to detecting incident radiation on a sub-element by means of the instantaneous photoelectric current. Such a device is not suitable for determining, for example, the radiation energy or the diameter of a beam.
The above-mentioned Patent Application moreover describes a picture display device having a radiation-sensitive semiconductor device for beam positioning and track following. The semiconductor device comprises inter alia a so-called quadrant diode, a photosensitive diode constructed from four sub-diodes. When such a quadrant diode is used in a device for beam focusing, for example, the device shown in German Offenlegungsschrift No. 25 01 124 which uses an astigmatic beam, a very accurate positioning of the incident beam with respect to the center of the quadrant diode is necessary. In addition, extra optical auxiliary means are often necessary for such methods; in the above example, for example, a cylinder lens is used to obtain an astigmatic beam.